CVE-2026-43216
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
A vulnerability in the Linux kernel's skb_may_tx_timestamp() function can cause a deadlock when handling TX timestamps in hardware interrupt context. The issue stems from improper use of the sk_callback_lock, which must not be taken in IRQ context.
Risk Assessment
A deadlock may freeze the system or crash network drivers, disrupting network services and potentially causing data loss.
Recommendation
Immediately update the Linux kernel to a version containing the fix that removes the lock and replaces it with RCU and READ_ONCE/WRITE_ONCE mechanisms.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net: Drop the lock in skb_may_tx_timestamp() skb_may_tx_timestamp() may acquire sock::sk_callback_lock. The lock must not be taken in IRQ context, only softirq is okay. A few drivers receive the timestamp via a dedicated interrupt and complete the TX timestamp from that handler. This will lead to a deadlock if the lock is already write-locked on the same CPU. Taking the lock can be avoided. The socket (pointed by the skb) will remain valid until the skb is released. The ->sk_socket and ->file member will be set to NULL once the user closes the socket which may happen before the timestamp arrives. If we happen to observe the pointer while the socket is closing but before the pointer is set to NULL then we may use it because both pointer (and the file's cred member) are RCU freed. Drop the lock. Use READ_ONCE() to obtain the individual pointer. Add a matching WRITE_ONCE() where the pointer are cleared.